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kaiser: kaiser_flush_tlb_on_return_to_user() check PCID

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Let kaiser_flush_tlb_on_return_to_user() do the X86_FEATURE_PCID
check, instead of each caller doing it inline first: nobody needs
to optimize for the noPCID case, it's clearer this way, and better
suits later changes.  Replace those no-op X86_CR3_PCID_KERN_FLUSH lines
by a BUILD_BUG_ON() in load_new_mm_cr3(), in case something changes.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hugh Dickins 2017-11-04 18:43:06 -07:00 committed by Greg Kroah-Hartman
parent 0651b3ad99
commit 8eaca4c7d9
3 changed files with 9 additions and 9 deletions
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4
arch/x86/include/asm/tlbflush.h
View File

@ -157,7 +157,7 @@ static inline void __native_flush_tlb(void)
* back:
*/
preempt_disable();
if (kaiser_enabled && this_cpu_has(X86_FEATURE_PCID))
if (kaiser_enabled)
kaiser_flush_tlb_on_return_to_user();
native_write_cr3(native_read_cr3());
preempt_enable();
@ -216,7 +216,7 @@ static inline void __native_flush_tlb_single(unsigned long addr)
*/
if (!this_cpu_has(X86_FEATURE_INVPCID_SINGLE)) {
if (kaiser_enabled && this_cpu_has(X86_FEATURE_PCID))
if (kaiser_enabled)
kaiser_flush_tlb_on_return_to_user();
asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
return;

6
arch/x86/mm/kaiser.c
View File

@ -436,12 +436,12 @@ void kaiser_setup_pcid(void)
/*
* Make a note that this cpu will need to flush USER tlb on return to user.
* Caller checks whether this_cpu_has(X86_FEATURE_PCID) before calling:
* if cpu does not, then the NOFLUSH bit will never have been set.
* If cpu does not have PCID, then the NOFLUSH bit will never have been set.
*/
void kaiser_flush_tlb_on_return_to_user(void)
{
this_cpu_write(x86_cr3_pcid_user,
if (this_cpu_has(X86_FEATURE_PCID))
this_cpu_write(x86_cr3_pcid_user,
X86_CR3_PCID_USER_FLUSH | KAISER_SHADOW_PGD_OFFSET);
}
EXPORT_SYMBOL(kaiser_flush_tlb_on_return_to_user);

8
arch/x86/mm/tlb.c
View File

@ -39,7 +39,7 @@ static void load_new_mm_cr3(pgd_t *pgdir)
{
unsigned long new_mm_cr3 = __pa(pgdir);
if (kaiser_enabled && this_cpu_has(X86_FEATURE_PCID)) {
if (kaiser_enabled) {
/*
* We reuse the same PCID for different tasks, so we must
* flush all the entries for the PCID out when we change tasks.
@ -50,10 +50,10 @@ static void load_new_mm_cr3(pgd_t *pgdir)
* do it here, but can only be used if X86_FEATURE_INVPCID is
* available - and many machines support pcid without invpcid.
*
* The line below is a no-op: X86_CR3_PCID_KERN_FLUSH is now 0;
* but keep that line in there in case something changes.
* If X86_CR3_PCID_KERN_FLUSH actually added something, then it
* would be needed in the write_cr3() below - if PCIDs enabled.
*/
new_mm_cr3 |= X86_CR3_PCID_KERN_FLUSH;
BUILD_BUG_ON(X86_CR3_PCID_KERN_FLUSH);
kaiser_flush_tlb_on_return_to_user();
}